PCB-Mounted Laser Substrate for Low-Inductance Distance Sensing
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Solution Overview
Problem
Optoelectronic distance meters face challenges in achieving high accuracy and signal quality due to parasitic inductance in laser diodes, electromagnetic interference, and crosstalk effects, which affect the precision and reliability of distance measurements.
Innovation Solution
A transmitting unit for optoelectronic distance meters is designed with a housing-less semiconductor laser substrate applied directly to a circuit board, reducing supply line inductance and optimizing the electrical connections to minimize electromagnetic interference and crosstalk, while using burst-modulated radiation for improved signal-to-noise ratio and distance measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional laser diode with housing and supply lines is used, then the laser diode is mechanically protected and easier to handle, but parasitic inductance increases and electromagnetic interference rises
Solution Approach 1:
The invention extracts the laser diode from its conventional housing and mounts the bare semiconductor substrate directly onto the circuit board. This eliminates the housing and supply line structures that generate parasitic inductance, while the laser diode remains functional. The bare substrate is electrically connected directly to the driver circuit through optimized trace routing, achieving both mechanical integration and electrical performance improvement.
Solution Approach 2:
The invention merges the laser diode substrate with the circuit board by directly mounting the semiconductor substrate onto the PCB. This integration eliminates the physical separation and intermediate connections that would introduce inductance. The laser diode becomes part of the circuit board structure itself, with electrical connections made through optimized trace routing rather than external supply lines.
2Ease of manufacture
If conventional laser diode mounting is used, then assembly is simpler, but electromagnetic interference and crosstalk increase
Solution Approach 1:
The invention replaces the conventional mechanical housing and wire-based electrical connections with a planar circuit board mounting approach. The bare semiconductor substrate is mounted directly on the PCB and electrically connected through copper traces, eliminating the mechanical housing structure and wire inductance that cause electromagnetic interference. This substitution maintains assembly simplicity while dramatically reducing EMI.
3Device complexity
If standard supply line routing is used, then circuit board layout is easier, but lead inductance increases reducing measurement precision
Solution Approach 1:
The invention applies local quality optimization by creating specialized low-inductance trace routing patterns in the critical areas where electrical connections are made to the laser diode. The circuit board layout incorporates features such as wide traces, minimal loop areas, and direct connection paths specifically at the laser diode mounting location, while other areas of the board can use standard routing practices. This localized optimization reduces inductance without requiring complete redesign of the entire board layout.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances distance measurement accuracy, increases measurement rate, and improves signal quality by reducing parasitic inductance and electromagnetic interference, allowing for precise and efficient distance determination with reduced component count and complexity.
Implementation Method 1
a laser driver (5) and a housingless semiconductor laser substrate (1) mounted on the printed circuit board (4)
Implementation Method 2
The surface of the target object reflects at least part of the optical signal back, usually in the form of diffuse reflection
Implementation Method 3
The reflected optical radiation is converted into an electrical signal by a photosensitive element in the device
Data Source
Figure 1
Figure 2a~3
Figure 4a~4b
AI summary
The invention relates to an optoelectronic distance measuring device, comprising a transmitting unit and comprising a receiving unit of an electronic evaluating unit. The transmitting unit has a circuit board, a semiconductor laser, and a laser diode driver for transmitting high-frequency intensity-modulated optical radiation. In order to receive a component of the optical radiation reflected by a target object by means of a photosensitive electrical component, the receiving unit is equipped with an electrical output signal as a received signal, a conditioning unit for conditioning the received signal, and an analog/digital converter for digitizing the conditioned received signal. The electronic evaluating unit determines a distance from the distance measuring device to the target object on the basis of a signal propagation time using the digitized received signal. The semiconductor laser is attached to the circuit board as a laser substrate that does not have a housing.